An alignment layer is disposed on a glass substrate of an LCD panel. The alignment layer is generally made of polyamide material. During manufacturing of the LCD device, rubbing operation is conducted so as to form several parallel grooves on the alignment layer to align the liquid crystal molecules in the same direction.
Referring to FIG. 1, a rubbing cloth 10 is wrapped around an alignment roller 11 by means of two-sided adhesive tape. The rubbing cloth 10 rubs against the alignment layer disposed on the glass substrate 12 upon rotation of the roller 11. After the rubbing operation, the alignment layer is formed with a plurality of parallel alignment grooves 122 that enable the molecules 121 in the alignment layer to be aligned with the alignment grooves 122. Once contaminated due to rubbing, the rubbing cloth 10 is required to be cleaned up, then the alignment layer 10 is eligible for conducting the rubbing operation again. In case, the dirt on the rubbing cloth 10 is not removed thoroughly and when the rubbing operation is conducted by using the contaminated rubbing cloth 10, the parallel alignment grooves in the alignment layer may surfer from uneven depth distribution after the rubbing operation, which, in turn, may affect the pre-tilt angle of the crystal molecules in the alignment layer.
Referring to FIG. 2, in order to thoroughly remove the dirt 14 on the rubbing cloth 10, a blank glass substrate is passed through the roller 11 in such a manner to rub against the rubbing cloth 10 so as to suck up the dirt 14, thereby cleaning the rubbing cloth 10.
Some disadvantages resulting from the use of the aforesaid roller 11 are as follows:    (i) Replacing a new rubbing cloth 10 on the roller 11 brings lots of inconveniences to the user. To discard the contaminated rubbing cloth 10 may result in extra expense, since the rubbing cloth is rather expensive;    (ii) Little cleaning effect is achieved with the use of the blank glass substrate. The glass substrate 13 can remove only some portion of the dirt 14;    (iii) The contaminated glass substrate needs to be discarded, since the glass substrate cannot be recycled, thereby resulting in environmental pollution and extra manufacture cost; and    (iv) Cleaning of the rubbing cloth 10 by using the blank glass substrate 13 may interrupt the manufacturing processes of the LCD device, since the roller 11 itself is used for rubbing against the alignment layer in order to form the alignment grooves thereon.